Pick Invite friends in the Workspace group on the left of Settings. It is the same screen if you go in with a work open.
The one line at the top is the rule. 3 friends a month = 1 month of Pro. Each extra friend earns $10 in credits (up to 10/mo).
Your invite link
The Your invite link field on the Invite card holds an address starting with pensiv.so/referral/. The string on the end is the referral code, issued one per account. Click Copy and it changes to Link copied for a moment. Before it is issued, Preparing your link… is shown.
There is no way to send an invitation by email yet.
One invite link is issued per account, and this field is the only route for inviting.
Rewards this month
Friends joined counts qualified friends in the form 3 / 10, and if any invite has not qualified yet, N waiting to qualify is attached beneath it. Credits earned is the amount built up at $10 per friend past the third, and Rewards claimed is the number of times you pressed claim.
A friend has to sign up and then finish email verification before they cross over to qualified. The counting unit is a calendar month, so it starts over each month.
Claim your rewards
Rows of 1 month of Pro or $10 in credits stack up, and each row carries the date it was earned and a Claim button. Earned rewards bank until you claim them. They do not vanish if you do not rush to press it.
A month of Pro comes in as a 30-day free period on an account that is not yet on Pro, and as credits if you are already on Pro or above. During the free period, Pro active — N days left appears, and the same notice shows on the Billing tab. If you subscribe to Pro during that time, paid billing starts only after the period ends, so you do not pay twice over.
If the numbers do not change right away, click Refresh at the top right. Friends qualify outside the app, so the screen is a beat behind.
Invite history
Invite history keeps one row per invited email, with the join date or Pending following on the right.
On the invited side
A friend who came in through your link sees a notice on the Billing tab: A friend sent you 50% off your first month of Pro — applied at checkout. Works on Pro yearly too. There is no separate field for entering a code; it is applied at checkout on its own. 
